Studies On Photosynthetic Characteristics Of Oil-tea Camellia Clones At The Fat Conversion Period Of Fruit

The diurnal variation of photosynthesis and light response curves were studied by the Lcpro+ultra compact photosynthesis system at the fat conversion period of fruit in September 2008 and 2009 in six Camellia oleifera clones, namely, Cenxi soft-branch 2, Cenxi soft-branch 3, Cenxi soft-branch 24, Gui 8, Xianglin 11 and Ganwu 1, which were bred in Guangxi, Hunan and Jiangxi, respectively. The purpose of this study is to lay a solid theoretical foundation for high photosynthetic efficiency breeding, and to select camellia clones which have the characteristics of tolerance to strong sunlight in northern tropical areas and the outermost southern subtropical localities, by identifying the reference indicators of high-quality photosynthesis beneficial to oil-tea camellia. The results are as follows:1. Diurnal variations of Pn of six oil-tea camellia clones presented a single peak curve or a double-peak curve. When the midday depression of photosynthes occurred to some extent, the double-peak curve was displayed. This phenomenon was mainly attributable to stomatal limitation. The average of Pn of six oil-tea camellia clones are all above 8μmolCO2·m-2·s-1, ranked in the descending order of Cenxi soft-branch 2, Cenxi soft-branch 3, Cenxi soft-branch 24, Ganwu 1, Gui 8, and Xianglin 11. Diurnal variations of Tr and WUE showed that Cenxi soft-branch 2 and 3 could use water better.2. Light response curves of the six Camellia clones showed that the range of LSP were between 1165.07μmol·m-2·s-1 and 1373.63μmol·m-2·s-1, while LCP concentrated in the range of 7.33 to 50.91μmol·m-2·s-1. Among them, Cenxi soft-branch 2 had a wider adaptability to light environment than others with its high LSP and low LCP, Gui 8 had a strong light-tolerant capacity. And Xianglin 11, Cenxi soft-branch 24, Cenxi soft-branch 2 and 3 had a stronger ability in weak light condition. The results also suggested that Cenxi soft-branch 2 and 3 had a greater photosynthetic potential.3. The leaf age has a great influence on Pn, Pn of one-year-old leaves was higher than that of 2-year-old leaves and tender leaves, thus one-year-old leaves served as major function leaves of photosynthesis. 4. There had significant difference in the chlorophyll content among these six clones, a highly significantly positive correlation was identified between Pn and Chlb, and Chlb/ChlT, with the pearson correlation coefficient are 0.910,0.861, respectively. There is no significant correlation betweent Pn and total chlorophyll, The relationship between Pn and carotenoid content revealed a significantly negative correlation, and the pearson correlation coefficient was -0.833.5. Correlation analysis showed that:There was a highly significantly positive correlation between Pn and fruit yield, a certain positive correlation between Pn and oil production, and a lesser negative correlation between Pn and oil conten t of fresh fruit.6. The main ecological factors which affect Pn and Tr most were PAR, followed by Ta and RH, and the main physiological factors wre Gs and Ci.